|
Apologies if this has been answered before, but I can't find it anywhere. I know the max recommended supply voltage is 15v. But, what is the minimum recommended? I have a 9.9v lithium pack I was thinking about re-purposing for a /p power supply.
73
--
- Matthew nj4y
|
I think the Nano wants to see 7V or more on its regulator. I know I saw that somewhere, but I've slept since then...
Jack, W8TEE
On Wednesday, April 25, 2018, 2:54:55 PM EDT, Matthew Stevens <matthew@...> wrote:
Apologies if this has been answered before, but I can't find it
anywhere. I know the max recommended supply voltage is 15v. But, what is
the minimum recommended? I have a 9.9v lithium pack I was thinking about
re-purposing for a /p power supply.
73
--
- Matthew nj4y
|
7v min for the 7805 on the Raduino is about right.
Most of the uBitx analog circuitry will probably be more or less working at 7v, but I don't really know.
It was all designed with 12v in mind.
I doubt you will get much RF out of the transmitter at 7v.
Some have reported hearing signals from the receiver with power off while the Raduino is connected?
to a USB host for downloading firmware, the host's 5v going back through the Raduino's 7805 to run the receiver.
15v is the absolute max spec for a good TDA2822.? (The WX clones can explode at 10v)
But at 15v the 7805 and some transistors and resistors will be getting hotter than they should.
If using with a battery pack that might exceed 13v, I'd recommend including
a low dropout regulator such as the LM2940-12 to power the main uBitx board (but not the IRF510's).
toggle quoted message
Show quoted text
On Wed, Apr 25, 2018 at 01:35 pm, Jack Purdum wrote:
I think the Nano wants to see 7V or more on its regulator. I know I saw that somewhere, but I've slept since then...
?
|
Put a DC to DC converter between
the battery and the uBitx.
On 4/25/2018 5:17 PM, Jerry Gaffke via Groups.Io wrote:
toggle quoted message
Show quoted text
7v min for the 7805
on the Raduino is about right.
Most of the uBitx analog circuitry will probably be more or less
working at 7v, but I don't really know.
It was all designed with 12v in mind.
I doubt you will get much RF out of the transmitter at 7v.
Some have reported hearing signals from the receiver with power
off while the Raduino is connected?
to a USB host for downloading firmware, the host's 5v going back
through the Raduino's 7805 to run the receiver.
15v is the absolute max spec for a good TDA2822.? (The WX clones
can explode at 10v)
But at 15v the 7805 and some transistors and resistors will be
getting hotter than they should.
If using with a battery pack that might exceed 13v, I'd recommend
including
a low dropout regulator such as the LM2940-12 to power the main
uBitx board (but not the IRF510's).
On Wed, Apr 25, 2018 at 01:35 pm, Jack Purdum wrote:
I think the Nano wants to see 7V or more on its
regulator. I know I saw that somewhere, but I've slept since
then...
?
|
Check the datasheet per device. I dropped mine to ~8V by resistor- just what was to hand in the junkbox.
|
On Wed, Apr 25, 2018 at 01:35 pm, Jack Purdum wrote:
I think the Nano wants to see 7V or more on its regulator
Correct! ? -- John - WA2FZW
|
Thanks for the replies! I am still awaiting my bitx (ordered April 12), so it will be awhile until I can try. I'm guessing the 9,9v nominal pack should work fine, probably a bit low on the power out but we shall see once my unit arrives!
73,
- Matthew nj4y
toggle quoted message
Show quoted text
On 4/25/2018 5:49 PM, John P wrote: On Wed, Apr 25, 2018 at 01:35 pm, Jack Purdum wrote:
I think the Nano wants to see 7V or more on its regulator
Correct!
--
John - WA2FZW
|
We need to study the minimum voltage needed for relay operation. If we can change the relays to5V type, and use a LDO regulator on raduino, we can work at 6V battery for the rig except that we may have to provide higher voltage for the HF linear? final section. May be, the bias arrangements of the pre-amp, driver and power amp need to be tweaked.
regards ?sarma ?vu3zmv
On Thu, Apr 26, 2018 at 12:24 AM, Matthew Stevens <matthew@...> wrote: Apologies if this has been answered before, but I can't find it anywhere. I know the max recommended supply voltage is 15v. But, what is the minimum recommended? I have a 9.9v lithium pack I was thinking about re-purposing for a /p power supply.
73
--
- Matthew nj4y
|
Sarma, if we look at setting up the uBITX for a minimal supply voltage operation we will need to also include minimal dropout regulators to the RF amplifier stages too. Then the resistors values will need to be recalculate for all stages to maintain the gain throughout the bidirectional RF amplifiers. This sounds like an interesting idea try.
toggle quoted message
Show quoted text
On Apr 26, 2018, at 01:20, Mvs Sarma < mvssarma@...> wrote: We need to study the minimum voltage needed for relay operation. If we can change the relays to5V type, and use a LDO regulator on raduino, we can work at 6V battery for the rig except that we may have to provide higher voltage for the HF linear? final section. May be, the bias arrangements of the pre-amp, driver and power amp need to be tweaked.
regards ?sarma ?vu3zmv
|
Have received my uBITx but haven't started assembling yet... I was thinking along similar lines, using 6V to power the board, and using 24V for the PA... Does it make sense to change out the 7805 voltage regulator for something different to make this work? Thx, Calvin VE3EIT
toggle quoted message
Show quoted text
On Thursday, April 26, 2018, Skip Davis via Groups.Io <skipnc9o= [email protected]> wrote: Sarma, if we look at setting up the uBITX for a minimal supply voltage operation we will need to also include minimal dropout regulators to the RF amplifier stages too. Then the resistors values will need to be recalculate for all stages to maintain the gain throughout the bidirectional RF amplifiers. This sounds like an interesting idea try. We need to study the minimum voltage needed for relay operation. If we can change the relays to5V type, and use a LDO regulator on raduino, we can work at 6V battery for the rig except that we may have to provide higher voltage for the HF linear? final section. May be, the bias arrangements of the pre-amp, driver and power amp need to be tweaked.
regards ?sarma ?vu3zmv
|
I have powered the bitx40 with a 3 cell lipo. Never dropped it below 11.4.?
|
I thought the input voltage (e.g., 7V) had to be at least 2V greater than the output voltage (5V), or is that only for buck converters. (Software guy here...not hardware.)
Jack, W8TEE
On Thursday, April 26, 2018, 12:35:48 PM EDT, vajra guru <vajraguru99@...> wrote:
Have received my uBITx but haven't started assembling yet... I was thinking along similar lines, using 6V to power the board, and using 24V for the PA... Does it make sense to change out the 7805 voltage regulator for something different to make this work? Thx, Calvin VE3EIT
On Thursday, April 26, 2018, Skip Davis via Groups.Io <skipnc9o= [email protected]> wrote: Sarma, if we look at setting up the uBITX for a minimal supply voltage operation we will need to also include minimal dropout regulators to the RF amplifier stages too. Then the resistors values will need to be recalculate for all stages to maintain the gain throughout the bidirectional RF amplifiers. This sounds like an interesting idea try. We need to study the minimum voltage needed for relay operation. If we can change the relays to5V type, and use a LDO regulator on raduino, we can work at 6V battery for the rig except that we may have to provide higher voltage for the HF linear? final section. May be, the bias arrangements of the pre-amp, driver and power amp need to be tweaked.
regards ?sarma ?vu3zmv
|
The board is designed to operate at 12v.
I doubt it will work very well at 6v.
That said, in answer to your question, an LM2940-5 has a lower dropout voltage than the LM7805:
??
?
The "Dropout Voltage" at the bottom of page 5 of the LM2940c datasheet says worst case at 1 Amp is 1 Volt.
But the Raduino pulls far less than 1 Amp, likely well under a half volt.? So would work with 5.5v going in.
Near the bottom of page 6 of the second datasheet above (covers both LM340 and LM7805)
it says the "Dropout Voltage" is "typically" 2 volts at 1 Amp, they don't give a worst case.
Will probably be less than 2v since the Raduino is not pulling much current, but you'd be on very
shaky ground if trying to feed it only 6v.
Jerry, KE7ER
toggle quoted message
Show quoted text
On Thu, Apr 26, 2018 at 09:35 am, vajra guru wrote:
Have received my uBITx but haven't started assembling yet... I was thinking along similar lines, using 6V to power the board, and using 24V for the PA... Does it make sense to change out the 7805 voltage regulator for something different to make this work? Thx, Calvin VE3EIT
|
My ubitx main board pulls about .6amp in transmit when the PA is fed from a separate power supply. tim ab0wr On Thu, 26 Apr 2018 11:00:23 -0700 "Jerry Gaffke via Groups.Io" <jgaffke@...> wrote: The board is designed to operate at 12v.
I doubt it will work very well at 6v.
That said, in answer to your question, an LM2940-5 has a lower
dropout voltage than the LM7805:
The "Dropout Voltage" at the bottom of page 5 of the LM2940c
datasheet says worst case at 1 Amp is 1 Volt. But the Raduino pulls
far less than 1 Amp, likely well under a half volt.? So would work
with 5.5v going in.
Near the bottom of page 6 of the second datasheet above (covers both
LM340 and LM7805) it says the "Dropout Voltage" is "typically" 2
volts at 1 Amp, they don't give a worst case. Will probably be less
than 2v since the Raduino is not pulling much current, but you'd be
on very shaky ground if trying to feed it only 6v.
Jerry, KE7ER
On Thu, Apr 26, 2018 at 09:35 am, vajra guru wrote:
Have received my uBITx but haven't started assembling yet... I was
thinking along similar lines, using 6V to power the board, and
using 24V for the PA... Does it make sense to change out the 7805
voltage regulator for something different to make this work? Thx,
Calvin VE3EIT
|
Good to know.
The discussion thus far is mostly about the LM7805 linear regulator on the Raduino.
The TDA2822 and LM7805 set definite max and min voltages, but nobody
really knows over what range of supply voltages the remainder of the
analog circuits in the rig will operate properly.
toggle quoted message
Show quoted text
On Thu, Apr 26, 2018 at 01:18 pm, Tim Gorman wrote:
My ubitx main board pulls about .6amp in transmit when the PA is fed
from a separate power supply.
tim ab0wr
|
Thanks folks, great info... 73 de VE3EIT
toggle quoted message
Show quoted text
On Thursday, April 26, 2018, Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote: Good to know.
The discussion thus far is mostly about the LM7805 linear regulator on the Raduino.
The TDA2822 and LM7805 set definite max and min voltages, but nobody
really knows over what range of supply voltages the remainder of the
analog circuits in the rig will operate properly.
On Thu, Apr 26, 2018 at 01:18 pm, Tim Gorman wrote:
My ubitx main board pulls about .6amp in transmit when the PA is fed
from a separate power supply.
tim ab0wr
|
Depends upon the regulator, but the general rule is about 2v… ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator – North American QRO Group at Groups.IO. ? email:? bill@... ? ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Jack Purdum via Groups.Io
Sent: Thursday, April 26, 2018 12:21 PM
To: [email protected]
Subject: Re: [BITX20] minimum supply voltage? I thought the input voltage (e.g., 7V) had to be at least 2V greater than the output voltage (5V), or is that only for buck converters. (Software guy here...not hardware.) On Thursday, April 26, 2018, 12:35:48 PM EDT, vajra guru <vajraguru99@...> wrote: Have received my uBITx but haven't started assembling yet... I was thinking along similar lines, using 6V to power the board, and using 24V for the PA... Does it make sense to change out the 7805 voltage regulator for something different to make this work? Thx, Calvin VE3EIT
On Thursday, April 26, 2018, Skip Davis via Groups.Io <skipnc9o=[email protected]> wrote: Sarma, if we look at setting up the uBITX for a minimal supply voltage operation we will need to also include minimal dropout regulators to the RF amplifier stages too. Then the resistors values will need to be recalculate for all stages to maintain the gain throughout the bidirectional RF amplifiers. This sounds like an interesting idea try. We need to study the minimum voltage needed for relay operation. If we can change the relays to5V type, and use a LDO regulator on raduino, we can work at 6V battery for the rig except that we may have to provide higher voltage for the HF linear? final section. May be, the bias arrangements of the pre-amp, driver and power amp need to be tweaked. regards ?sarma ?vu3zmv
? On Thu, Apr 26, 2018 at 12:24 AM, Matthew Stevens <matthew@...> wrote: Apologies if this has been answered before, but I can't find it anywhere. I know the max recommended supply voltage is 15v. But, what is the minimum recommended? I have a 9.9v lithium pack I was thinking about re-purposing for a /p power supply.
73
--
- Matthew nj4y
?
|
When I simulate the PA at 6VDC I get about 750 mW from it… ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator – North American QRO Group at Groups.IO. ? email:? bill@... ? ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Thursday, April 26, 2018 1:00 PM
To: [email protected]
Subject: Re: [BITX20] minimum supply voltage ? The board is designed to operate at 12v.
I doubt it will work very well at 6v.
That said, in answer to your question, an LM2940-5 has a lower dropout voltage than the LM7805:
??
?
The "Dropout Voltage" at the bottom of page 5 of the LM2940c datasheet says worst case at 1 Amp is 1 Volt.
But the Raduino pulls far less than 1 Amp, likely well under a half volt.? So would work with 5.5v going in.
Near the bottom of page 6 of the second datasheet above (covers both LM340 and LM7805)
it says the "Dropout Voltage" is "typically" 2 volts at 1 Amp, they don't give a worst case.
Will probably be less than 2v since the Raduino is not pulling much current, but you'd be on very
shaky ground if trying to feed it only 6v.
Jerry, KE7ER
On Thu, Apr 26, 2018 at 09:35 am, vajra guru wrote: Have received my uBITx but haven't started assembling yet... I was thinking along similar lines, using 6V to power the board, and using 24V for the PA... Does it make sense to change out the 7805 voltage regulator for something different to make this work? Thx, Calvin VE3EIT
|
Skip Davis
_Dave_ AD0B
K9HZ